1. Field of the Invention
The present invention relates to an apparatus for manufacturing a semiconductor device. It also relates to a method of forming the same.
2. Description of the Related Art
Memory devices, such as those used in computers, are just one of many widely used semiconductor devices. From a functional point of view, it is required that semiconductor devices operate at a rapid speed and simultaneously have a great amount of storage capacity. To meet these requirements, technologies for fabricating semiconductor devices have been developed to improve their degree of integration, reliability, and response speed.
In particular, as design rules have decreased for improving the degree of integration of semiconductor devices, a gate insulating layer is required to have a thin thickness and a small width in semiconductor devices such as a highly integrated dynamic random access memory (DRAM), a static random access memory (SRAM), a flash memory, etc. A gate oxide layer having a thickness of below about 10 Å is demanded in a logic circuit that drives a memory circuit.
On the other hand, process integration has been promoted in the semiconductor industry to meet technological and economical requirements. The process integration is defined as carrying out complex processes performed in different process chambers in a single cluster tool. The single cluster tool includes several chambers that are interconnected by a platform to continuously perform different processes.
Various methods for manufacturing semiconductor devices using a cluster tool are known in the art. For instance, a method of forming a gate oxide layer of a semiconductor device is disclosed in Korean Patent Laid Open Publication No. 2001-0004969. According to the method, a sheet-off process is performed on a surface of an active region provided on a substrate to remove a native oxide layer formed on the surface of the active region. An aluminum oxide layer is formed on the surface of the active region in an atomic layer deposition (ALD) chamber. The aluminum oxide layer is annealed in a reacting furnace under an N2O atmosphere to remove defects in the aluminum oxide layer, and to form an oxide nitride layer between the substrate and the aluminum oxide layer. A polysilicon layer is formed on the aluminum oxide layer. A word line including tungsten silicide, titanium silicide or tungsten is formed on the polysilicon layer.
When the substrate is, however, transported to the reacting furnace, vacuum may not be provided to the substrate. This causes growth of a native oxide layer on the aluminum oxide layer. As a result, it may be impossible to form a gate oxide layer having a thickness of below about 15 Å due to the native oxide layer.
Further, a cluster tool having high-pressure and heat-treatment chamber, and a method of forming a thin layer using the same are disclosed in Korean Patent Laid Open Publication No. 2002-0030994. A cluster tool includes a polyhedral transfer chamber for providing an isolated space in which a substrate is transferred. A load-lock chamber is connected to a first side face of the transfer chamber. Process chambers are connected to second side faces of the transfer chamber. A batch type high-pressure and heat-treatment chamber is connected to a third face of the transfer chamber. The substrate that is processed in the process chambers is loaded into the high-pressure and heat-treatment chamber. A substrate transferring member transports the substrate between the load-lock chamber, the process chambers and the high-pressure and heat-treatment chamber.
Since the batch type high-pressure and heat-treatment chamber is employed in the cluster tool, a native oxide layer grows on a gate oxide layer formed on the substrate to a thickness of above about 10 Å. A gate electrode formed on the gate oxide layer having a thicker thickness may deteriorate the reliability of a semiconductor. It may be difficult to form a gate oxide layer having a thickness of below about 15 Å using the conventional cluster tool. Furthermore, the substrate may be transported to another chamber for forming a gate electrode or a contact electrode. Accordingly, even though a gate oxide layer having a thickness of below about 15 Å may be formed using the conventional cluster tool, a native oxide layer may grow on the gate oxide layer during transportation of the substrate. The gate oxide layer may not have a desired thickness owing to the native oxide layer. The native oxide layer may include particles that deteriorate performance and reliability of a semiconductor.